1. Field of the Invention
The present invention relates to a gas turbine engine comprising a centrifugal compressor for compressing air that is drawn or sucked into the compressor, a compressed air passage for supplying the air compressed by the compressor to a burner, and a turbine driven by means of combustion gas generated in the burner. The compressor and the turbine are positioned on a rotating shaft adjacent to each other in the axial direction.
2. Description of the Prior Art
Japanese Patent Application Laid-open No. 11-117810 discloses an arrangement in which, in order to prevent curvature in a rotor system due to a difference in temperature caused by natural convection of the air inside a gas turbine engine after operation of the engine is stopped, a hollow cylindrical heat pipe cover surrounding a high temperature part and a low temperature part of the engine, is provided to eliminate the difference in temperature.
In a small-sized gas turbine engine, since the compressor and the turbine are placed to be extremely close to each other in the axial direction of the rotating shaft, the heat on the turbine side, through which hot combustion gas is passing, is transmitted directly to the compressor side, and the air temperature around the entrance of the compressor increases thereby degrading the air compression performance, which is a problem. Moreover, since the higher the air temperature emitted from the compressor, the higher the fuel burning efficiency of the burner, if a heat exchange can be carried out between the air supplied to the burner and the combustion gas without providing a heat exchanger having a complicated structure, the performance of the gas turbine engine can be enhanced without increasing its size.
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to provide a thermal insulator between a turbine and a compressor of a gas turbine engine and at the same time enable the air that has passed through the compressor to be heated by the heat of the hot turbine.
In order to achieve the above-mentioned object, there is proposed a gas turbine engine comprising a centrifugal compressor for compressing air that is sucked into the compressor, a compressed air passage supplying the air compressed by the compressor to a burner, and a turbine driven by means of combustion gas generated in the burner. The compressor and the turbine are positioned on a rotating shaft, to be adjacent to each other in the axial direction, wherein evaporation sections on the radially inner side of a plurality of heat pipes provided in a radial form, face towards the outer periphery of the rotating shaft between the compressor and the turbine, and condensation sections on the radially outer side of the heat pipes face towards the compressed air passage.
In accordance with the above-mentioned arrangement, it is possible to absorb the heat on the turbine side by means of the evaporation sections of the heat pipes thus preventing the heat from being transmitted to the compressor side and thereby suppressing degradation in the air compression efficiency of the compressor. Moreover, it is possible to transmit the heat on the turbine side to the compressed air passage via the condensation sections, thereby heating the air passing through the passage to enhance the combustion efficiency in the burner.
In addition, there is proposed a gas turbine engine wherein an air bearing is formed between the inner periphery of the evaporation sections of the heat pipes and the outer periphery of the rotating shaft.
In accordance with the above-mentioned arrangement, oscillation of the rotating shaft can be suppressed by the air bearing and the rotating shaft can rotate smoothly. Moreover, the engine becomes oil-less due to the use of the air bearing and it becomes unnecessary to use accessories such as an oil pump thus further reducing the size.
Further, there is proposed a gas turbine engine wherein a large number of channels inclined towards or orthogonal to the circumferential direction, are formed on the inner periphery of the evaporation sections of the heat pipes.
In accordance with the above-mentioned arrangement, the repulsive force of the air membrane of the air bearing can be increased by the large number of channels formed on the inner periphery of the evaporation sections thus enhancing the performance in supporting the rotating shaft.
Further, there is proposed a gas turbine engine wherein the width of the inner periphery of the evaporation sections of the heat pipes facing the outer periphery of the rotating shaft, is increased in the axial direction of the rotating shaft.
In accordance with the above-mentioned arrangement, since the area over which the outer periphery of the rotating shaft and the inner periphery of the evaporation sections of the heat pipes forming the air bearing face each other increases, the performance in supporting the rotating shaft can be enhanced.
There is also proposed a gas turbine engine wherein the evaporation sections of at least two adjacent heat pipes communicate with each other.
In accordance with the above-mentioned arrangement, the operating fluid is able to move among a plurality of heat pipes and each of the heat pipes can exhibit an equal heat transport performance.
Further, there is proposed a gas turbine engine wherein the evaporation sections of all the heat pipes communicate with each other.
In accordance with the above-mentioned arrangement, the operating fluid is able to move among all of the plurality of heat pipes and each of the heat pipes can exhibit a more equal heat transport performance.
Also, there is proposed a gas turbine engine wherein the condensation sections of the heat pipes in the compressed air passage, form diffusers.
In accordance with the above-mentioned arrangement, since the condensation sections themselves of the heat pipes in the compressed air passage form diffusers, a diffuser function can be exhibited without increasing the number of parts.
Further, there is proposed a gas turbine engine wherein the evaporation sections of the heat pipes extending radially between the compressor and the turbine, are curved in the circumferential direction.
In accordance with the above-mentioned arrangement, the ability to absorb heat can be enhanced by increasing the length of the evaporation sections of the heat pipes and the thermal insulating of the compressor from the turbine can be carried out effectively.
Also, there is proposed a gas turbine engine wherein the condensation sections of the heat pipes in the compressed air passage are curved in the circumferential direction.
In accordance with the above-mentioned arrangement, the heat release performance can be enhanced by increasing the length of the condensation sections of the heat pipes and the air passing through the compressed air passage can be heated effectively.
Still further, there is proposed a gas turbine engine wherein the compressed air passage and the heat pipes are divided into a plurality of modules by a plane that includes the rotating shaft.
In accordance with the above-mentioned arrangement, since the compressed air passage and the heat pipes are divided into a plurality of modules, the ease of assembly when assembling them on the outer periphery of the rotating shaft, can be enhanced.